Piston skirt expander



April 9, 1935.v R. R. TEEToR PISTON SKIRT EXPANDER Filed April 12, 1953EU/GWW.'

Patented Apr. 9, 1935 UNITED sTATEs PATENT OFFICE PISTON SKIRT EXPANDERApplication April 12, 1933, Serial No. 665,718

Claims. (Cl. 309-12) My invention relates more particularly to anexpanding device for expanding the split skirt of a piston of aninternal combustion engine and the like in order to overcome defects insuch 5 pistons, particularly after the same have become Worn.

It is well known that pistons, particularly when provided with splitskirts of aluminum or similar material, wear quickly with the resultthat Athere is piston "slap and excessive oil consumption and blow-by.The principal object of my invention is to provide a simple and improvedpiston skirt expander which eliminates these defects. More particularly,I provide an expander comprising two half sections formed of leaf springmetal and so shaped as to cooperate together to expand the skirt. Theexpander is quite wide lengthwise ofthe piston and is formed toaccommodate a piston skirt having a tapering inside Wall.

With the above and incidental objects in view the invention consists incertain novel features of construction and combination of parts, theessential elements whereof are recited in the appended claims and twoforms of embodiments of which are described in detail hereinafter andillustrated in full in the accompanying drawing, which forms part ofthis specification.

Figure 1 is a side view of the piston partially broken away to show partof the expander in position within the piston;-

Fig. 2 is a longitudinal section taken on the line 2-2 of Fig. 1;

Fig. 3 is a bottom plan view of the piston with the expander;

Fig. 4 is a perspective view of the expander shown in Figs. 1 to 3; and

Fig. 5 is a perspective view of another form of my expander.

Referring rst to Figs. 1, 2 and 3, the piston. shown in these gures forillustrative purposes is preferably formed of aluminum alloy andcomprises a head 1, a skirt 8, and struts 9 on the skirt connected tothehead. The struts 9 carry the piston pin bosses I2. Except where thestruts 9 join the head, the skirt is separated from the head bycircumferential slots I6. On one side the skirt is provided with avertical slot I5 extending from its upper to its lower edge.

50 The expander, as shown in Figs. l to 4, comprises two complementaryhalves |1 each formed from a strip of spring or leaf steel. Each end ofeach half is curved or curled and these curved ends of the two halvespress against each other. Each half is also provided with an opening |9through which the piston pin |||a is adapted to extend when the expanderis in position in the piston. Each end of each half has a recess 20forming the curved tongues 2| at the rear and tongues 2liL at the frontend. The lower edge of 5 each tongue 2|a is bent outwardly to provide asharp protruding lip 22. Similar lips may be formed on the lower edge ofthe lower tongues 2| if desired. Vertical ribs or bends 24 may beprovided to increase the expansion action of the expander.

It will be observed that when the expander is not in the piston skirt,the lower tongue 2|a projects outwardly considerably beyond the uppertongue 2|a. The wall of the piston skirt (Fig. 2) tapers in thicknessfrom top to bottom, theinterior of `the skirt being of lesser diameterat the top than at the bottom.

When the expander is to be inserted in the piston, the two halves arebrought together as 20 shown in Fig. 4, land then -contracted crosswiseand lengthwise by hand or by any desired means. With the expander inthis condition it is inserted into the skirt and then released whereuponit assumes the position shown in Figs. 1 to 3 with the sides pressingagainst the facing ends of the pin bosses I2, the tongues 2 la pressingoutwardly against the skirt adjacentthe vertical slot l5 and the tongues2| pressing outwardly against the skirt opposite the slot l5. The lips22 bite into the metal of the skirt and aid in locking the expander inplace.

It will be apparent from the foregoing that the expander tends to expandthe piston skirt so that the latter at all times snugly fits thecylinder wall. The cooperating curved tongues at each end afford a highdegree of expansive force which acts directly against the skirt at rightangles to the piston pin and also against the pistonv pin bosses in thedirection. of the piston pin. As the 40 upper' tongues 2 I'r1 areshorter than the lower tongues 2| a, the expander is more easilyinserted into the tapered skirt and the upper tongues 2| and 2|EL arepermitted to exert substantially the same pressure against the skirt asthe' lower 45 tongues 2| and 2 |a so that the skirt is more evenly oruniformly expanded. p

'The form of expander shown in Fig. 5 accommodates a diierent type ofpiston, particularly one in which the piston pin is adjacent the upperend of the skirt or the construction of the piston otherwise requiresthat the major portion ofl the expander be below the piston pin. 'I'hehalf sections of the expander have curved tongues 25 at one end adaptedto engage the skirt adjacent the vertical slot I5. The other ends haveL-shaped tongues 29 adapted to have their bends 21 engage the skirtopposite the slot and their iianges 28 to press against each other.Elongated openings 30 are adjacent the top edges of the half sections toreceive the piston pin. Narrow elongated openings 3l accommodate otherprotuberances on the piston.

It is apparent that changes may be made without departing irom thespirit of the invention.

I claim:

1. A piston skirt expander elongatedin shape and adapted to extendacross the skirt, the expander being formed of leaf spring metal andcomprising two half-sections each formed at each end with two tongues,the tongues at at least'one end being curved inwardly and thecorresponding tongues on the two half-sections being in rm engagementwhen assembled in the piston.

2. 'I'he combination of a piston having a skirt with a vertical slot,the interior wall of the skirt being tapered, of an expander formed ofwide leaf spring and comprising two half-sections adapted to extendacross theiskirt, said half-sections being shaped to form in assembledrelation an elongated gure having at each end a plurality of upper and aplurality of lower separated expansible formations adapted to engage thepiston wall, the bottom portion of the expander including said lowerexpansible formations being longer than the upper portion to accommodatethe tapered wall of the piston skirt and effect uniform expansion of theskirt.

3. A piston skirt expander elongated in shape and adapted to extendacross the skirt, the expander being formed of leaf spring metal andcomprising two half-sections each formed at each end with two tongues,the tongues at at least one end being curved inwardly and thecorresponding tongueson the two half-sections being in firm engagementwhen assembled in the piston, and the lower tongues at at least one endo1' the half-sections being longer than the upper tongue on such end.

4, An expander adapted to be inserted into a piston skirt having avertical slot and an interior tapered wall, the expander being formed ofwide leaf spring metal shaped to form an elongated iigure, and theexpander having at each end upper curved tongues and longer lower curvedtongues, the upper tongues engaging each other and the longer tonguesengaging each other and forming expansion formations, such tongues alsoengaging the interior tapered. wall ot the piston skirt.

5. An expander adapted to be inserted into a piston skirt having avertical slot formed of spring metal .comprising complementalhalf-sections,`

each said half-section comprising a central web having oppositelyprojecting tongues inclined, diagonally inwardly to engage similarlyinclined tongues on the other of said complemental formed half-section.

